1. Field of the Invention
The present invention relates to an agent for treating textile materials. The present invention particularly relates to a treating agent capable of improving the light fastness of synthetic textile materials such as polyesters which are degraded or changed in color by light.
2. Description of the Related Art
Those synthetic textile materials which are composed of polyester, nylon, etc., and which are required to have a high degree of durability and light fastness, for example, carpets, car seats, car mats, seat belts, and the like, are generally processed by the use of a dye bath or printing paste, and a light fastness-improving agent in combination. The light fastness is improved, for example, by causing the fibers to adsorb 2-(2'-hydroxy-3'-t-butyl-5'-methylphenyl)-5-chlorobenzotriazole (Compound I) of the formula ##STR3## by the use of a dye bath in combination with the aqueous dispersion of Compound I as disclosed in Japanese Unexamined Patent Publication (Kokai) Nos. 60-59185 and 2-41468.
A dyed material obtained by the procedure surely exhibits a fastness rating of 3 to 4 in a light exposure test (irradiation at 83.degree. C. for 200 hours) by a high temperature fadeometer, and the use of the light fastness-improving agent improves the fastness by at least one rating. However, the dyed material is generally subjected to heat setting at 160.degree. to 190.degree. C. after dyeing in practical processing. As a result, Compound I sublimes from fibers when the dyed material has been treated with an aqueous dispersion of Compound I, and there arise problems that the effect of improving the light fastness falls, and that the sublimed material further adheres to the apparatus for heat setting to cause a disadvantage. The dyed material is, therefore, required to be treated at a temperature as low as from 140.degree. to 150.degree. C. at a cost to the setting effect. Accordingly, processing factories are encountering many difficulties in maintaining the productivity and a certain degree of quality of the dyed material. Furthermore, when the dyed material is subjected to such a dry heat treatment at 200.degree. to 210.degree. C. for 2 to 5 minutes as is conducted in the dyeing processing of seat belts, that is, processing by the so-called thermosol method, Compound I sublimes, and the effect of improving the light fastness is completely lost. Furthermore, when a textile material is subjected to processing including printing, for example, processing in which the textile material is pretreated with an aqueous dispersion of Compound I, printed with a printing paste, and fixed by high temperature (HT) steaming at 170.degree. to 180.degree. C. for 7 to 8 minutes, Compound I adsorbed by the pretreated fibers sublimes during the treatment at a high temperature as mentioned above, and the effect of improving the light fastness is almost lost. In addition, even when an aqueous dispersion of Compound I is used in the printing paste in combination, Compound I similarly sublimes during HT steaming, and the effect of improving the light fastness in pattern portions cannot be obtained. Since Compound I itself has a yellow color, it has a disadvantage in that it changes the color shade of a textile material (especially a textile material dyed in a pale color) when used.
Furthermore, the dimming of windowpanes in vehicles has recently become a problem. In those vehicles in which textile materials such as car seats and car mats have been processed with a dispersion of Compound I are used, Compound I gradually sublimes, and there arises a problem that the transparency of the windowpanes in the vehicle is lowered. This is a serious problem from the standpoint of safety, and a quick solution of the problem is desired.
On the other hand, Japanese Unexamined Patent Publication (Kokai) No. 4-91274 discloses that 2-{2'-hydroxy-3'-(3",4",5",6"-tetrahydrophthalimidomethyl)-5'-methylphenyl } benzotriazole (Compound II) of the formula ##STR4## and 2,2'-dihydroxy-4,4'-dimethoxybenzophenone (Compound III) of the formula ##STR5## are useful for improving the light fastness of polyester fibers subjected to dyeing operations involving high temperature treatment.
Compound II exhibits a low degree of sublimation and an excellent effect of preventing a decrease in the strength of the fibers caused by light. However, it has drawbacks that its effect of preventing the change in color caused by light is somewhat weak compared with conventional treating agents, and that it exhibits whitening and yellowing caused by optical decomposition of the compound itself in a light fastness test run over a long period of time by exposure using a xenon light source which is said to have a wavelength close to that of the sunlight. Accordingly, Compound II cannot be practically used. Since Compound III itself displays a yellow color to a high degree, textile materials particularly those processed with a pale color dye are discolored. Accordingly, Compound III cannot be used. In addition, when a fiber material is treated with Compound III and dyed simultaneously, Compound III tends to adhere to the body of the dyeing apparatus after the completion of the treatment. As a result, problems such as staining of the processed fabric tend to arise.
Japanese Patent Application No. 4-347028 discloses that 1,4-bis(4-benzoyl-3-oxyphenoxy)butane (Compound IV) of the formula ##STR6## and 2-(2'-hydroxy-4'-methoxyphenyl)-4,6-diphenyl-s-triazine (Compound V) of the formula ##STR7## are useful for improving the light fastness of a dyed polyester textile material which is subjected to high temperature treatment. Compounds IV and V surely exhibit a low degree of sublimation, and are excellent in the effect of preventing a decrease in the strength of the fibers caused by light. Moreover, the use of these compounds eliminates such problems as the dimming of windowpanes in vehicles caused by the sublimation of the compounds.
However, these compounds exhibit poor adsorption on cation-dyeable polyester textile materials which are now being used for car seats, etc., and, therefore, do not improve the light fastness of such fibers.